Heart Failure With Preserved Ejection FractionNCT05723679
Targeting Breathing Limitations to Improve Functional Outcomes in HFpEF
A study testing HeO2 gas mixture and Room air gas mixture in people with Heart Failure With Preserved Ejection Fraction and Obesity, run by University of Texas Southwestern Medical Center at 1 site in United States.
Trial summary
The overall purpose of this study is to investigate whether pulmonary limitations that increase the oxygen (O2) cost of breathing impact dyspnea on exertion (DOE) and peak exercise capacity in patients with HFpEF and obesity. Read more about this study
- Who is it for?
- Ages 55 to 90 yearsHealthy volunteers can take part
- Conditions the study is for
- Heart Failure With Preserved Ejection Fraction, Obesity
- What is being tested?
- HeO2 gas mixture and Room air gas mixture
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 78 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jul 2023to 30 Jun 2029
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 55 to 90 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- signs and symptoms of heart failure
- an ejection fraction > 0.50;
- objective evidence of diastolic dysfunction. elevated biomarkers (NT-proBNP >300 ng/dl) or HF hospitalization
- healthy volunteers
Who cannot join
- age < 55 years
- BMI > 50 kg/m2
- Atrial fibrillation with poorly controlled heart rate
- phosphodiesterase type 5 (PDE5) inhibitor use
- severe valvular disease
- severe Chronic obstructive pulmonary disease (COPD)
- Chronic kidney disease (CKD) 4 or higher
- any restriction of ambulation and mobility.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
UT Southwestern Medical Center
Dallas, Texas, 75390
Raksa B Moran, RN, 2143456574, raksamoran@texashealth.org
Jessica N Alcala, RN, 2143456574, jessicaalcala@texashealth.org
About this study
Official title: Targeting Breathing Limitations to Improve Functional Outcomes in Heart Failure With Preserved Ejection Fraction (HFpEF)
The overall purpose of this study is to investigate whether pulmonary limitations that increase the oxygen (O2) cost of breathing impact dyspnea on exertion (DOE) and peak exercise capacity in patients with HFpEF and obesity. As per investigator's hypothesis, obesity is likely a significant contributor to DOE and exercise intolerance in patients with HFpEF.
Read the detailed description
Clinical screening tests including cardiopulmonary exercise testing (CPET), pulmonary function testing, and dual-energy x-ray absorptiometry (DEXA) scans will be performed on all subjects. Investigator's approach will be to undertake the following objectives:
Objective 1: (Observational) is a cross-sectional study designed to test the interaction of HFpEF (underlying changes in pulmonary function) and obesity (obesity-related changes in pulmonary function) on the O2 cost of breathing, and its association with DOE and peak exercise capacity. The specific hypotheses proposed to test as part of this objective are:
Hypothesis 1.1: Due to the presence of obesity-related mechanical ventilatory constraints, the O2 cost of breathing will be greater in obese HFpEF patients and obese controls vs. nonobese HFpEF patients and nonobese controls, but will be similar between obese HFpEF patients vs. obese controls.
Hypothesis 1.2: The association between the O2 cost of breathing and DOE and the association between the O2 cost of breathing and peak exercise capacity will be stronger in obese HFpEF patients and obese controls vs. nonobese HFpEF patients and nonobese controls, but will be similar between obese HFpEF patients vs. obese controls.
Objective 2: (Interventional) is a single-blind, randomized, placebo-controlled, cross-over trial designed to investigate the effects of reducing obesity-related mechanical ventilatory constraints by breathing a HeO2 gas mixture (HeO2: 21% O2 and 79% He) on DOE and peak exercise capacity. The specific hypotheses proposed to test as part of this objective are:
Hypothesis 2.1: HeO2 will decrease DOE in obese HFpEF patients and obese controls, but not in nonobese HFpEF patients or nonobese controls, as HFpEF- or cardiovascular-related limitations will not be affected by HeO2.
Hypothesis 2.2: HeO2 will increase peak exercise capacity in obese HFpEF patients and obese controls, but not in nonobese HFpEF patients or nonobese controls as HFpEF- or cardiovascular-related limitations will not be affected by HeO2.
Study Day 1:
This visit consists of a consenting process (including medical Hx , DEXA scan, and pulmonary function testing. Goals of this day are to determine fat and lean mass and to quantify pulmonary function. This visit will usually last between 3 - 3.5 hours. Any subjects who demonstrate severe pulmonary disease at this point will be excluded.
Study Day 2:
This visit will consist of O2 cost of breathing tests, as well as submaximal and maximal CPET tests. This visit is designed to test Hypotheses 1.1 and 1.2. and will usually last between 3 - 3.5 hours.
Study Day 3 and 4:
These visits consist of submaximal and maximal CPET tests with either breathing room air or HeO2 gas mixtures on separate days. These visits are designed to test Hypotheses 2.1 and 2.2. and will usually last between 2 - 2.5 hours.
The Diagnostic test including : 1) Submaximal and maximal cardiopulmonary exercise test 2) pulmonary function testing 3) Eucapnic Voluntary Hyperventilation 3) Dual-Energy X-Ray absorptiometry (DEXA), are the procedures that will be performed by the participants for investigator to gather data (observational) and assess DOE, peak exercise capacity, pulmonary function, body composition, and O2 cost of breathing between study groups.
- Being tested
- HeO2 gas mixture, Room air gas mixture
- Keywords
- exertional dyspnea, exercise intolerance, HFpEF, breathing limitations, cardiopulmonary physiology
- Medical subject headings
- Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
HeO2 gas mixtureOther
Low-density helium-oxygen gas mixture (HeO2: 21% O2 and 79% He). Participant will be breathing this gas mixture.
Room air gas mixtureOther
Normal room air
| Study group | Role | What they receive |
|---|---|---|
| HeO2 gas mixture, then Room air gas mixture | Experimental | Participant will be randomized to each intervention on separate days (Study visit 3 and 4) in this cross-over trial. Participants that receive HeO2 first will then receive the room air gas mixture. At least 24 hours will separate each visit. Receives: Other: HeO2 gas mixture; Other: Room air gas mixture |
| Room air gas mixture, then HeO2 gas mixture | Experimental | Participant will be randomized to each intervention on separate days (Study visit 3 and 4) in this cross-over trial. Participants that receive Room air first will then receive the HeO2 mixture. At least 24 hours will separate each visit. Receives: Other: HeO2 gas mixture; Other: Room air gas mixture |
What is being measured
The primary outcome is the main question the study is designed to answer.
O2 cost of breathing (Objective 1)
O2 cost of breathing measured during eucapnic voluntary hyperventilation, and calculated using oxygen uptake and ventilation variables.
Measured: Day 2
Change in DOE during HeO2 breathing (Objective 2)
Dyspnea on Exertion (DOE) will be assessed via ratings of perceived breathlessness (RPB) using a 0-10 Borg Scale, and will be compared with that measured during room air breathing.
Measured: Day 3 or 4
Change in peak exercise capacity during HeO2 breathing (Objective 2)
Peak exercise capacity will be assessed by measuring peak oxygen uptake (in L/min, measured via a breath-by-breath metabolic measurement system), peak power output recorded from a cycle ergometer (Watts), and/or total exercise duration (minutes).
Measured: Day 3 or 4
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Feb 2023
- Study start1 Jul 2023
- Primary completion30 Jun 2028 (estimated)
- Study completion30 Jun 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Heart Failure With Preserved Ejection FractionStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Mechanistic Clinical Trial
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 78 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Texas Southwestern Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Bryce Balmain, University of Texas Southwestern Medical Center
- Investigators
- Tony G Babb, Ph.D., Principal investigator, University of Texas Southwestern Medical CenterBryce N Balmain, Ph.D., Principal investigator, University of Texas Southwestern Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05723679
- Sponsor's protocol ID
- STU-2022-1174
- Status last verified
- May 2026
- First submitted
- 27 Jan 2023
- Last updated
- 7 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Targeting Breathing Limitations to Improve Functional Outcomes in Heart Failure With Preserved Ejection Fraction (HFpEF)
- ClinicalTrials.gov ID
- NCT05723679
- Acronym / sponsor ID
- STU-2022-1174
- Keywords
- exertional dyspnea, exercise intolerance, HFpEF, breathing limitations, cardiopulmonary physiology
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 78 participants (estimated)
- Lead sponsor
- University of Texas Southwestern Medical CenterUniversity, hospital or other
- Study start
- 1 Jul 2023 (actual)
- Primary completion
- 30 Jun 2028 (estimated)
- Study completion
- 30 Jun 2029 (estimated)
- First posted
- 13 Feb 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The overall purpose of this study is to investigate whether pulmonary limitations that increase the oxygen (O2) cost of breathing impact dyspnea on exertion (DOE) and peak exercise capacity in patients with HFpEF and obesity. As per investigator's hypothesis, obesity is likely a significant contributor to DOE and exercise intolerance in patients with HFpEF.
Detailed description
Clinical screening tests including cardiopulmonary exercise testing (CPET), pulmonary function testing, and dual-energy x-ray absorptiometry (DEXA) scans will be performed on all subjects. Investigator's approach will be to undertake the following objectives:
Objective 1: (Observational) is a cross-sectional study designed to test the interaction of HFpEF (underlying changes in pulmonary function) and obesity (obesity-related changes in pulmonary function) on the O2 cost of breathing, and its association with DOE and peak exercise capacity. The specific hypotheses proposed to test as part of this objective are:
Hypothesis 1.1: Due to the presence of obesity-related mechanical ventilatory constraints, the O2 cost of breathing will be greater in obese HFpEF patients and obese controls vs. nonobese HFpEF patients and nonobese controls, but will be similar between obese HFpEF patients vs. obese controls.
Hypothesis 1.2: The association between the O2 cost of breathing and DOE and the association between the O2 cost of breathing and peak exercise capacity will be stronger in obese HFpEF patients and obese controls vs. nonobese HFpEF patients and nonobese controls, but will be similar between obese HFpEF patients vs. obese controls.
Objective 2: (Interventional) is a single-blind, randomized, placebo-controlled, cross-over trial designed to investigate the effects of reducing obesity-related mechanical ventilatory constraints by breathing a HeO2 gas mixture (HeO2: 21% O2 and 79% He) on DOE and peak exercise capacity. The specific hypotheses proposed to test as part of this objective are:
Hypothesis 2.1: HeO2 will decrease DOE in obese HFpEF patients and obese controls, but not in nonobese HFpEF patients or nonobese controls, as HFpEF- or cardiovascular-related limitations will not be affected by HeO2.
Hypothesis 2.2: HeO2 will increase peak exercise capacity in obese HFpEF patients and obese controls, but not in nonobese HFpEF patients or nonobese controls as HFpEF- or cardiovascular-related limitations will not be affected by HeO2.
Study Day 1:
This visit consists of a consenting process (including medical Hx , DEXA scan, and pulmonary function testing. Goals of this day are to determine fat and lean mass and to quantify pulmonary function. This visit will usually last between 3 - 3.5 hours. Any subjects who demonstrate severe pulmonary disease at this point will be excluded.
Study Day 2:
This visit will consist of O2 cost of breathing tests, as well as submaximal and maximal CPET tests. This visit is designed to test Hypotheses 1.1 and 1.2. and will usually last between 3 - 3.5 hours.
Study Day 3 and 4:
These visits consist of submaximal and maximal CPET tests with either breathing room air or HeO2 gas mixtures on separate days. These visits are designed to test Hypotheses 2.1 and 2.2. and will usually last between 2 - 2.5 hours.
The Diagnostic test including : 1) Submaximal and maximal cardiopulmonary exercise test 2) pulmonary function testing 3) Eucapnic Voluntary Hyperventilation 3) Dual-Energy X-Ray absorptiometry (DEXA), are the procedures that will be performed by the participants for investigator to gather data (observational) and assess DOE, peak exercise capacity, pulmonary function, body composition, and O2 cost of breathing between study groups.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- Mechanistic Clinical Trial
| Arm | Type | Receives |
|---|---|---|
| HeO2 gas mixture, then Room air gas mixture | Experimental | Other: HeO2 gas mixture, Other: Room air gas mixtureParticipant will be randomized to each intervention on separate days (Study visit 3 and 4) in this cross-over trial. Participants that receive HeO2 first will then receive the room air gas mixture. At least 24 hours will separate each visit. |
| Room air gas mixture, then HeO2 gas mixture | Experimental | Other: HeO2 gas mixture, Other: Room air gas mixtureParticipant will be randomized to each intervention on separate days (Study visit 3 and 4) in this cross-over trial. Participants that receive Room air first will then receive the HeO2 mixture. At least 24 hours will separate each visit. |
Who may qualify
- Ages
- 55 to 90 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- signs and symptoms of heart failure
- an ejection fraction > 0.50;
- objective evidence of diastolic dysfunction. elevated biomarkers (NT-proBNP >300 ng/dl) or HF hospitalization
- healthy volunteers
Key exclusion criteria (8 listed)
- age < 55 years
- BMI > 50 kg/m2
- Atrial fibrillation with poorly controlled heart rate
- phosphodiesterase type 5 (PDE5) inhibitor use
- severe valvular disease
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| HeO2 gas mixtureLow-density helium-oxygen gas mixture (HeO2: 21% O2 and 79% He). Participant will be breathing this gas mixture. | Other | HeO2 gas mixture, then Room air gas mixture, Room air gas mixture, then HeO2 gas mixture |
| Room air gas mixtureNormal room air | Other | HeO2 gas mixture, then Room air gas mixture, Room air gas mixture, then HeO2 gas mixture |
Primary outcome
O2 cost of breathing (Objective 1)
Time frame: Day 2
O2 cost of breathing measured during eucapnic voluntary hyperventilation, and calculated using oxygen uptake and ventilation variables.
Change in DOE during HeO2 breathing (Objective 2)
Time frame: Day 3 or 4
Dyspnea on Exertion (DOE) will be assessed via ratings of perceived breathlessness (RPB) using a 0-10 Borg Scale, and will be compared with that measured during room air breathing.
Change in peak exercise capacity during HeO2 breathing (Objective 2)
Time frame: Day 3 or 4
Peak exercise capacity will be assessed by measuring peak oxygen uptake (in L/min, measured via a breath-by-breath metabolic measurement system), peak power output recorded from a cycle ergometer (Watts), and/or total exercise duration (minutes).
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 May 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Tony G Babb, Ph.D. principal investigator
University of Texas Southwestern Medical Center
Bryce N Balmain, Ph.D. principal investigator
University of Texas Southwestern Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing HeO2 gas mixture and Room air gas mixture in people with Heart Failure With Preserved Ejection Fraction and Obesity, run by University of Texas Southwestern Medical Center at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 7 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Raksa B Moran, RN (214-345-6574, raksamoran@texashealth.org), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
O2 cost of breathing (Objective 1) (time frame: Day 2). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 May 2026.